Joseph bennett hill



Patented Mar. 8, 1932 UNITED STATES PATENT .orrlcs JOSEPH BENNETT HILL,PHILADELPHIA, PENNSYLVANIA, ASSIGNOB TO IRE BARRETT COMPANY, ACORPORATION OF NEW JERSEY rnocnss or mow-c sunrnomc acme Io Drawing.

M invention relates to the production of t etic tannin materials andmore especlally to the pro notion of sulphonic acid de'- rivatives freefrom free sulphuric acid.

8 The common synthetic tanning materials are made as is well knownbyvsulphonating aromatic hydrocarbons or their derivatives, such asphenol, naphthalene, anthracene, carbazole, etc., and either using thesesulphonic acids so produced without further treatment for tanningpurposes or condensing them with formaldehyde, sulphur-monochloride orother condensing agents. In view of the fact that the chemistry of thecondensation reactions between the sulphonic acids and agents such asformaldehyde, sulphur monochloride and the like is not fully understood,I intend that the term condensing agent as used throughout thespecification 29 and claims shall include those materials which react inthe presence of sulphonic acids to effect condensation of either thesulphonic acids themselves or of the sulphonic acids with the agentsadded to effect the condensation reaction. The sulphonation of the h,

drocarbon as ordinarily effected cannot readily carried to completion onaccount of the accompanying dilution of the sulphuric acid, and,therefore, gives a sulphonic acid product containing a considerablepercent age of free sulphuric acid. The presence of this free sulphuricacid in the finished tannin material is considered harmful to the leater produced therefrom in that it tends to produce rotting in the leatheror ageing.

This effect may be partly eliminated by partially neutralizin thesulphonic acid or its condensation pro uct with soda, whereby thesulphuric acid being a somewhat stronger.

acid than the sulphonic acid,"is more com- Eletely neutralized than thesulphonic acid.

venthis treatment, however, is not wholly satisfactory and it is highlydesirable to actually remove or eliminate free sulphuric acid from thetanning material before it is used in the tanning process.

I have found that the well known procedure of efiecting the sulphonationunder reduced pressure, so as to vaporize out the water of reaction fromthe sulphonation mixture and Application fled October 8, 1824. SerialNo. 742,400.

While the above procedure is readily applicable to the sulphonation of alarge num-. ber of hydrocarbons without causin difliculty, there arecases, particularly w ere a low water insoluble content of the sulphonicacid is desired, to which the above process does not readily lend itselfon account of the fact,-for example, that under certain conditions oftemperature, concentration, etc., and where the sulphuric acid isexhausted or present in the sulphonation mixture in relatively smallamount, side reactions take place giving rise to the formation ofinsoluble compounds.

' I have found that thedifiiculties ma be overcome by a very simpleexpedient wit out materially affecting the quality of the product. Inthe sulphonation of naphthalene, for example, under reduced pressure,the formation of insoluble products does not appear, to begin until theremaining free sul huricacid gets down to the neighborhood of 5% of theysulphonation mix. The sulphonation can, therefore, be carried-this farwithout endangering the quality of the finished product. I 1

have found that this residual'sulphu'ric acid' j can be readily consumedin sulphonatingjs'ome lower boiling hydrocarbon, such as benzol or oneof its 'homologues, which causes the absorption or elimination of'theresidual free sulphuric acid due to its interaction with thesehydrocarbons to form the corresponding sulphonic acids at a lowertemaperature than that necessary when naphth ene alone: is sulphonated.These low boiling hydrocarbons are preferably added in quantity inexcess of that required to interact with the residual acid-and thisexcess may be removedafter the completion of the sulphonation bydistillation. The lower temperature used for this second sulphonationrelative to that maintained in sulphonating the naphthalene or similarcompounds is not conducive to the formation of insoluble compounds, andthis sulphonation can, therefore, be carried to completion and anyexcess of the more read- .ily sulphonatable hydrocarbons distilled offfraction from coal tar naphtha boiling approxima'ting between 150 C. and200 C. and consisting in large measure of the trimethylbenzenes which,like benzol, a compound hereinbefore referred to, are aromaticcompounds,

specifically of the benzene series.

While I do not wish to limit my invention to the sulphonation ofnaphthalene or to' any exact process for effecting this sulphonation,the following will serve as an example of the manner in which myinvention may be carried out.

One hundred and twenty pounds of refined naphthalene may be mixed with100 pounds of 66 B. sulphuric acid and heated to 160 C. for a period ofone hour. The sulphonator is put under a vacuum of about 22 inches ofmercury, below atmospheric pressure, and maintained at this pressure ata temperature of 155 C.160 C. for about one hour additional. The vacuumis interrupted, the temperature reduced to 130 C. in any convenient wayand 35 pounds of the fraction from coal tar na htha. boilingapproximately between 150 and 200 C. are added to the sulphonator andthe contents thoroughly agitated. Vacuum is again applied and the excessof hydrocarbons distilled oil". The product may be drawn off and useddirectly or may be condensed with formaldehyde in the usual mannor toform the synthetic tanning material.

I claim:

1. The process which comprises incompletely utilizing a quantity ofsulphuric acid added to an aromatic hydrocarbon for the sulphonationthereof, adding a more readily added to naphthalene for thesulplhonation thereof, adding a more readily sulp onatable compound ofthe benzene series to the sulphonation mixture; and causing the residualsulphuric acid to be absorbed in the sulphonation of said more readilysulphonatable compound.

3. The process which comprises incompletely utilizing a quantity ofsulphuric acid added to an aromatic hydrocarbon for the sulphonationthereof, adding a more readily sulphonatable aromatic compound to thesulphonation mixture in excess of the quantity needed to combine withthe residual sulphuric acid, causing the residual sulphuric acid to beabsorbed in the sulphonatlon of said more readily sulphonatable compoundand distilling off the excess of the more readily sulphonatablecompound.

4. The process which comprises incompletely utilizing a quanity ofsulphuric acid added to naphthalene for the sulphonation hydrocarbon bycausing it to interact with said acid under such conditions as to leavea small quantity of residual acid, then adding a more readilysulphonatable compound of the benzene series in quantity sufiicient tointeract with substantially all of said residual acid and causing saidcompound to be sulphonated by the residual sulphuric acid.

6. The process which comprises mixing with an aromaticv hydrocarbon atleast the theoretical quantity of sulphuric acid required for itssulphonation, sulphonating the hydrocarbon under reduced pressure undersuch conditions as to leave a small quantity of residual sulphuric acid,then adding a more readily sulphonatable aromatic compound in quantitysuflicient to interact with substantially all of said residualacid andcausing said compound to be sulphonated by the residul sulphuric acid.

7. The process which comprises mixing with an aromatic hydrocarbon atleast the theoretical quantity of sulphuric acid required for itssulphonation, sulphonating the hydrocarbon under such conditions as toleave a small quantity of residual sulphuric acid, then adding an excessof a more readily sulphonatable compound of the benzene series,

causing a portion thereof to be sulphonated by the residual sulphuricacid and distilling ofi the excess of the more readily sulphonatablecompound.

8. In the sulphonation of an aromatic hy drocarbon the step ofeliminating residual sulphuric acid contained in the sulphonation mixwhich comprises causin it to-react with a more readily sulphonata 1ehydrocarbon added thereto.

9. In the sulphonation of an aromatic hym drocarbon the steps whichcomprise eliminating residual sulphuric acid contained in thesulphonation mix by causing it to react with a more readilysulphonatable hydrocarbon added in excess thereto and removing theexcess of the latter by distillation.

10. In a process of sulphonating naphthalene by. reacting sulphuric acidtherewith, the improvements which comprise sulphonating the naphthaleneso as to leave at the completion of the sulphonation a quantity ofresidual acid in the sulphonation mixture equal to about 5% of thecontent thereof, then adding to said mixture a more readilysulphonatable compound of the benzene series and sulphpinating saidcompound with the residual 11. The process which comprises mixing withan aromatic hydrocarbon a quantity of sulphuric acid, sulphonating saidhydrocarbon until the sulphonation mix contains about 5% free sulphuricacid, then adding an excess of coal tar naphtha boiling between 150 C.and 200 C.

12. The process which comprises mixing approximately lbs. of 66 Baumsulphuric acid with lbs. of refined naphthalene, sulphonating saidnaphthalene until approximately 5% free sulphuric acid results, thenadding an excess of coal tar naph- 40 tha boiling between approximatelyand 200 C. and causing a portion thereof to be sulphonated by theresidual sulphuric acid.

13. A tanning composition comprising a sulphonated aromatic compound inadmix- 45 ture with a small -"quantity of a sulphonated derivative of amore readily sulphonatable aromatic compound.

14. A product as in claim 13 combined with formaldehyde. 8

60 15. A tanning composition comprising sulphonated naphthalene inadmixture with a small quantity of a sulphonated derivative of a morereadily sulphonatable compound of the benzene series.

" 16. A product as in claim 15 combined with formaldehyde.

In testimony whereof I aflix my signature.

JOSEPH BENNETT HILL.

